


Lance's Alien Encounter

by liddie



Category: Voltron: Legendary Defender
Genre: Aliens, Alternate Universe - Modern Setting, Alternate Universe - Space, Anal Sex, Explicit Sexual Content, Fuck Or Die, Humor, M/M, Mirror Sex, Monsterfucking, Mutual Pining, Shiro is a xenomorph, Size Difference, Smut, Spit As Lube, Tongue Fucking, Xenomorphs, Xenophilia, alien!Shiro, lance is lance
Language: English
Status: Completed
Published: 2019-02-14
Updated: 2019-02-14
Packaged: 2019-10-28 05:55:49
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 8,532
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/17781845
Author URL: https://archiveofourown.org/users/liddie/pseuds/liddie
Summary: On a routine mission Lance is sent to collect a few samples from planet LV-432. His pilot/bodyguard is Shiro, a xenomorph with a heart of gold. Lance has been on tons of missions with Shiro and although he hasn't seen his xenomorph form a lot, Shiro's human form is an embodiment of Lance's ideal guy, and Lance has been slowly working up the courage to ask him on a date. Maybe even when they finish up on LV-432 and get back to the main ship.Except, unlike the routine missions before, this one goes a little haywire and soon Shiro and Lance are stuck planetside with a fast approaching storm and Shiro beginning to act weird.But Lance won't let his friend suffer whatever this is alone, not when he's ready and willing tohelp.Or: the fic where xenomorph!Shiro fucks a very willing Lance.





	Lance's Alien Encounter

**Author's Note:**

  * For [Nsf_ko](https://archiveofourown.org/users/Nsf_ko/gifts).



> This is a gift for Ko!! Who also likes xenomorphs and has been watching the Alien series with me and listening to me babble about them🖤💙
> 
> This is 1000% self-indulgent and I can't deny it lol  
> Also, I took a bunch of facts/references/ideas about xenomorphs and mashed them together, so this world and Shiro's design is a mix of everything + my weird brain. You've been warned lol 
> 
> ps I'm sorry for the title 😭
> 
> You can see the alien that I based Shiro's body type off of [here](https://cdna.artstation.com/p/assets/images/images/006/993/270/large/peter-sandeman-petersandeman-aliencovenant-csizeposter-day-correct.jpg?1502885919) and [here!](https://vignette.wikia.nocookie.net/aliens/images/f/ff/XenomorphXX121.png/revision/latest?cb=20141005001209)  
> He is a good boy 💖
> 
> Ko made some absolutely stunning [Lance/xenomorph art](https://twitter.com/nsf_ko/status/1096219314850541568) for Valentine's Day, please give it lots of love! 🖤🖤

* * *

The small ship is quiet, only the hum of a few background systems generating the softest of noises. Lance sits on the bench in the living area, his protective suit stripped down around his waist.

“Shiro, just tell me what's wrong,” he murmurs after a few minutes of watching the man across from him.

They'd been out on the planet’s surface collecting a few samples and fixing one of the probes when Shiro had suddenly called off the mission. One minute Lance had been humming _‘Walking On Sunshine’_ to himself while adjusting a few of the probe’s sensors and the next there had been seven feet of sleek black xenomorph standing over him and Shiro's urgent voice in his head telling him to get inside.

And when an alpha prime xenomorph tells you to do something, you do it.

But now Shiro's in his human form and being stubbornly tight-lipped about the reason their mission was cut short. And he's acting strange, which only worries Lance more.

“Shiro,” Lance tries again but this time his pilot shakes his head.

Sitting up Shiro looks at Lance, the grey of his eyes much darker than usual. “Lance, I need you to go back to the ship.”

Lance hesitates a moment but nods. “Okay,” he agrees. “I'll prep the takeoff sequence and we'll be back with the others within an hour.”

“No,” Shiro says, a little sharper. “I mean you need to go back _alone_.”

“Alone?” Lance parrots, confused. “Why would I go back alone?” Lifting a hand he scratches at the side of his neck. “You mean leave the samples?”

Shiro shakes his head but a beeping sound pulls Lance's attention to the communication screens. He walks over to investigate and slides his hand across the panel, pushing the flashing icon.

A holographic weather map pops up, showing off an incoming storm.

“Well, it doesn't look like we’re going back to the ship yet. There's a storm rolling in and it looks like we're going to be stuck in here for a few hours, at least.”

“No,” Shiro shakes his head in sudden jerks. “You need to leave, _now_.”

“I can't.” Lance walks back over to Shiro and sits beside him. “Shiro, what's going on?” He's trying to stay calm and level-headed about all this but it's becoming more difficult. And Shiro isn't looking very good, either.

Shiro hangs his head, fingers twisted in his damp hair. “Just tell everyone I went AWOL. Tell them... tell them that I abandoned you and you had to leave without me.” His voice sounds rough, forced. His body moves in jerky motions, the rapid state of his breathing uneven. “You can tell them I attacked—”

“I’m not gonna do that!” Lance’s own voice is a little too high. He inhales deeply and then lets it out slow, placing a light hand on Shiro’s shoulder. “Shiro, they _know_ you,” he murmurs quietly. “No one’s gonna believe that.”

“You’ll have to make them believe it.”

Lance shakes his head although Shiro’s still looking at the ground. “Shiro, c’mon. If you’re sick I'll help you into bed and we can wait out the storm or until you feel better. Your health is more important than this mission anyway, there will be other opportunities.”

Shiro shakes his head sharply and Lance can feel something hard shift beneath his hand. He yanks it back on reflex. “I’m not sick,” Shiro says adamantly. His voice comes through gritted teeth. “Lance, you have to leave me here.”

“I’m not leaving you here! Are you even listening to yourself?” Shaking his head Lance moves to stand in front of Shiro and places both hands on his shoulders. “And it’s not just because I failed both test landings, I wouldn’t do it anyway. You’re my friend.”

The laugh Shiro lets out is shaky. When he raises his head Lance sees that his eyes are black, so dark he can see his own reflection in them. Lance’s hands tighten on Shiro’s shoulders but he doesn’t look away. “Lance, please. Just—”

“I’m not going to leave you here.” Wrapping his arms around Shiro’s head Lance hugs it against his stomach. His fingers pet through Shiro’s dark hair. “We’re gonna figure it out.”

Shiro lets out a sound that's halfway between a groan and a growl and pushes his face against Lance's stomach. He may be imagining things but it's almost like Shiro inhales deeply.

“Okay,” Lance says, scratching just behind Shiro's ears. “I'm going to go grab some water packets and then you're gonna tell me what's going on. Okay?”

Leaning back Shiro nods. “Yeah, okay,” he mumbles and Lance almost doesn't want to leave him alone.

But he pulls himself away and heads down the hallway leading to the ‘kitchen’ area.

 

* * *

 

“So you just need to fuck someone?”

“Essentially, yes.” Shiro wrings his hands. “It’s a biological thing. It’s never been an issue before but I haven’t been back here in so long and I feel…” He trails off, eyes growing hazy.

“I thought with xenomorph’s there’s a queen? That reproduction and eggs come from her?”

Tilting his head Shiro looks at Lance. “I’m not part of a hive, so I don’t have a queen. I don’t want one, and being off the planet helps. But I didn’t think coming back would be a problem and now my body has these urges.”

“Urges, huh?” Lance raises a hand slowly. “I volunteer as tribute,” he jokes lightly. “If you need to fuck someone…” Lance holds out his arms, motioning to the empty landscape around them. “I’m the clear choice here, yeah?”

“I can’t ask that of you, Lance.”

“I volunteered.” Lance places a hand on his hip. “And it’s not going to be a chore, you know? You’re gorgeous, Shiro. You don’t have to act like you don’t know that.”

Shiro’s head whips up but instead of laughing or smiling at the joke his face looks pained.

“What? What is it?” Stepping closer Lance places a hand on Shiro’s arm. “Shiro?”

Shaking his head Shiro lets out a sigh. Lance’s worry escalates the longer Shiro remains silent. He opens his mouth, then closes it. Finally he lets out a sigh and glances away. “I wouldn’t be in _this_ form.”

“You…” Lance trails off and then everything falls into place. His eyes widen comically. “Oh. Oh! You mean…”

Shiro nods solemnly.

“Oh, wow. Okay, well. That's uh…” Lance's babbling is incoherent, his cheeks flushed a light pink. His mouth opens and closes a few times, words starting and stalling. Finally he finds the courage to spit out what he wants to say. “It's not, you know, a deal breaker or anything.”

Shiro looks up at him like _he's_ the one technically classified as an alien. “What?”

“What?” Lance parrots back with a nervous laugh. He and Shiro stare at each other for a long moment before Lance sees the other man's body shudder again, trying to force a transformation back to its original state.

Burying one hand in his hair Shiro grabs the bench with the other, his grip denting the metal as it’s impacted. “Go lock yourself in the storage room,” Shiro grits out. “Somewhere without vents.”

Lance forgets his embarrassment and places a hand on Shiro's shoulder, trying to ground him. “I'm not going anywhere, Shiro. We're gonna do this and get you back to normal.”

Lifting his head Shiro looks at Lance with dark eyes, the irises and sclera pitch black. “Lance,” he says, fingers denting the metal further. “I don’t want to hurt you.”

“You are perfectly capable of snapping me in half in any form you’re in, Shiro.” Lance ignores the tingle that slides up his spine at the thought. He looks away, out through one of the small windows at the storm fast approaching. “You won’t hurt me. I’m 100% positive. So yeah, let’s do this. Me. You can do _me._ In any form. At any time, really. I’m gonna shut up now.”

When he turns back around Shiro is right there, so close Lance can smell a musty but cool scent rolling off him like cologne. “Are you sure?” He asks softly, as if Lance will bolt if he speaks too loud. “If we start, I don’t think I’ll be able to stop.”

In reply Lance cups Shiro’s cheeks and yanks him down to smash their lips together. The surprise is brief and Shiro presses into the kiss almost immediately, tongue sliding against Lance’s and eagerly dipping into his mouth. There’s a strange clicking sound coming from somewhere but Lance is too taken by Shiro’s mouth to give much thought to it.

His eyes drift shut and he barely notices Shiro’s hands drop from his body. Tilting his head Lance attempts to deepen the kiss, tongue sliding against Shiro’s. Their mouths become slick and wet the longer they make out, excessively so as the abundance of saliva slides down Lance’s chin.

When he goes to tease the tip of his tongue against Shiro’s Lance jerks his head back when it brushes against something sharp. Eyes flying open he lets out a shrill scream when he sees the xenomorph an inch from his face.

Lance’s hands push against the alien’s domed head (how did he not notice that replacing Shiro’s hair?) as he stumbles back, tripping and falling hard, body becoming wedged between the bench and the wall. The frantic racing of his heart is so loud that the rest of the crew must be able to hear it from the main ship orbiting the planet.

A sleek head pokes into his view. _‘Are you okay?’_

Lance groans, trying to lift himself up from the trapped position. “Jesus, Shiro. A little warning would’ve been nice.” He manages a sitting position and wipes an arm across his mouth and chin, looking up.

This isn't the first, second or even the fifth time Lance has seen Shiro's true form but he still feels that rush of excitement thrumming through his veins when the xenomorph straightens up, oblong head glossy beneath the bright light.

Despite years of studying the exoskeleton still looks so foreign, but Lance yearns to slide his fingers over the ridges and dips to feel the texture beneath his hands.

He wonders if Shiro's chest moves with his breathing.

‘ _You look as if you're trying to solve a puzzle.’_

“I am, I guess. Kind of.” With a little help from Shiro’s tail Lance makes it back onto his feet. He rubs at his elbow, glancing at Shiro patiently standing beside him. “You’re not in pain anymore?”

 _‘This form is easier to manage. I have more...restraint. Control?’_ Shiro’s head tilts to the side as if he’s thinking. _‘I don’t really know how to explain it. My human form is unnatural, so I...’_

Shiro continues to explain and Lance hums, only half paying attention. Leaning in a little closer he points to Shiro's back. “Can I touch these?” He lets his hand hover over one of the dorsal spines. He’s not on the right research team to have the opportunity to study the xenomorphs so closely, even dead ones. So he’s gonna use every bit of his new mission to sate his curiosity.

Shiro’s massive head dips in answer to his question and Lance takes it as a nod, wrapping his fingers around the dark appendage. It’s smooth and cool beneath his touch and he feels Shiro’s body shudder. _‘They’re sensitive,’_ he says simply.

“Are they sensory organs?” Lance traces along the dark spine, over the blunt end and down to where it connects with Shiro’s spine. He slides his thumb over a ridge there, leaning in close. “Do you use them to echolocate? Or maybe as a counterbalance.”

_‘Lance? I’ll answer whatever questions you have but my restraint will only last so long.’_

“Right, sorry.” Releasing the dorsal spine Lance comes back to stand in front of Shiro. He’s hunched over but he’s got to be a little over seven feet tall. Eyeing the xenomorph Lance swallows audibly, reaching to tug his shirt up and off. Might as well treat it like a bandage that needs to be removed quickly.  “Okay, we’re really doing this. Yep, gonna fuck an alien.”

Shiro’s head tilts to the side, his tail swaying back and forth behind him. It’s almost mesmerizing to watch.

Shaking his head the young researcher narrows his eyes at the xenomorph. “Are you looking at me?” When Shiro’s head perks back up at attention Lance quickly looks down at his fingers fumbling to unbutton his pants. “Do you even have eyes?” He wonders aloud, shoving his pants down and kicking them from around his ankles.

Amusement colors Shiro’s tone. _‘I can see you.’_

“I can see you, too, big guy. But I’m not really seeing…” Lance trails off, bending over to gather up his clothing. He looks at Shiro’s chest, then lower to his crotch. “Huh.” Lifting his head Lance frowns. “Where’s your dick?”

_‘It’s retractable. Having it exposed all the time would—’_

“A retractable dick,” Lance interrupts with a whistle, dumping his clothing on the bench. “What I wouldn’t have done for one of those when I was thirteen.”

_‘Are you uncomfortable?’_

“What?” Lance laughs, straightening up. It’s actually pretty cold in here and he wraps his arms around himself casually hoping Shiro doesn’t take it as some kind of defensive stance. “Why would you say that?”

 _‘You babble when you’re uncomfortable or nervous.’_ Shiro takes a step closer, his feet making no sound on the cool floor. _‘Having second thoughts?’_

“Pfff, you wish.” Lance drops his arms down to his sides. He raises his chin and stares down the xenomorph he’s had a crush on for ages. “I’m not afraid of you, Shiro,” he says, voice steady and true. “I’m just—this is my first time doing something like this so I’m a little out of my element. I mean, it’s not like I came on this mission prepared to be jumped by you.”

When Shiro speaks his voice sounds hesitant and almost intrigued. _‘Your first time?’_

“Having sex with an alien? Yeah. Are you really surprised?”

_‘Oh, right. I—of course.’_

Lance cracks a grin, hands on his hips as he leans toward Shiro. “You thought I meant my first time having sex? Were you..hoping for that?”

 _‘Shut up,’_ Shiro mumbles, turning away. If Lance had to guess, he’d say the xenomorph was embarrassed.

A shudder wracks Shiro’s frame and Lance’s smile slips. He walks over to Shiro and grabs at one of the dorsal spines, giving it a little tug. “Well, you’ll be my first alien encounter,” he says with a wiggle of his eyebrows, trying to ignore the nerves and excitement curling in his stomach.

Shiro makes a clicking sound and Lance claps his hands. “Okay, well. Where are we gonna do this? Here? The bedroom?”

 _‘Wherever you feel comfortable,’_ Shiro says, tail brushing against Lance as it swishes. _‘A bed is probably a good idea, though.’_

Humming in agreement Lance leads the way down the hall. “Are you in pain?” He asks belatedly.

_‘It’s nothing that isn’t manageable.’_

“I’ll take that as a yes,” Lance mumbles. They make it to the end of the hall, a door on either side. “Who’s roo—”

_‘Mine.’_

Lance can’t do anything but nod. “Right.” Placing his hand on the panel by the door he’s a little surprised it opens without needing an override code. “Huh.” He walks through the doorway and is hit with a sudden humid heat. Shiro’s room is dark, the only light coming from a recessed glow in the ceiling. The bed looks like it hasn’t been touched. “It’s very uh, homey.”

Shiro’s snort echoes in Lance’s head. The xenomorph stands in the doorway and watches Lance look around.

Turning to look at Shiro Lance places his hands on his hips. “Well, get in here. What are you, some kind of vampire that needs to be invited in?”

 _‘Sorry.’_ Walking into the room the doors close behind Shiro, his tail curling up over his head, tip swaying. _‘Are you sure—’_

“Your bed is made,” Lance says as he flops back onto the mattress. The sheets are crisp beneath his touch. “Do you make it every morning?”

 _‘That would imply that I use it at all.’_ When Lance sits up with a frown Shiro tips his head back to look up.

Following his gaze Lance sees the crosswork of beams overhead. There are markings scratched into the metal in specific spots and Lance looks down at Shiro once more, trying not to glance at the sharp claws on his hands and feet. He swallows audibly. “You sleep up there? Like a bat?”

 _‘Yeah, like a bat.’_ Shiro crouches beside the bed. An awkward silence settles over them.

Lance slaps his hands onto his thighs suddenly and Shiro jerks his head up. “Well, let’s get to it then.” Standing up he takes a deep breath, then goes to the panel on the wall. “I’m gonna turn the lights up a little, okay? Just so I can see what I’m doing.” Sliding a finger across the screen the lights grow brighter, not as harsh as the hallways and common area but enough that Lance can see properly.

Shiro stays in his spot, tail swaying like a cobra.

Walking back to the center of the room Lance levels his gaze on Shiro, doing his best to seem tall in his state of dress. “Listen, I’m just gonna blurt this out. I know you're in pain because you need to fuck something and whatnot. But you’re not fingering me open with those...claws.” Lance shudders at the thought. Shiro’s obsidian claws are long, hooked and lethal. His ass wouldn’t stand a chance. But a sudden thought strikes Lance and he looks around. “What are we gonna use as lube?”

Shiro opens his mouth, showing off multiple rows of needle thin but very sharp teeth and a tongue that rivals Venom’s.

Lance suddenly slaps a hand over his eyes. “Wait! I don’t want to see your inner jaw. It’s.. I’m sorry but it’s really creepy.”

_‘I’m not trying to show you that.’_

Peeking between his fingers Lance sees the thick, clear fluid dripping from Shiro’s mouth. “Oh. Oh!” He makes a face, nose twitching. “That’s... kinda gross but okay. When in Rome, right?”

He steps up to Shiro and reaches out, fingers trembling as they near the assortment of blades the xenomorph form has for teeth. Gently he slides his fingertips across Shiro’s lower jaw, gathering up a good amount of the fluid.

Lance opens and closes his fingers, watching the viscous saliva stretch with the movement. “Gross,” he whispers, although the tent at the front of his boxers tells a different story.

_‘Are you going to take off your underwear?’_

“Are you that eager to see me naked?” Lance fires back but there’s something earnest about the way Shiro's oblong head dips in a nod. It's almost..cute.

Cheeks flushing Lance turns around and uses his dry hand to push his boxers down, shoving them around his thighs until they drop from his knees. His shirt goes next, tossed into a pile on the floor. When he straightens up his back bumps into something cool, a shiver sliding down his spine.

“Uh, Shiro?” He whispers, keeping his eyes fixed forward. The hair on the back of his neck stands on end.

_‘You smell nice.’_

An obsidian claw reaches forward, hovering along Lance's side to gently brush his hip. The babble spills freely from Lance’s mouth. “Like um, a sexy nice? Or an ‘I can't help my instincts and want to eat you’ nice?”

Shiro's voice echoes like a whisper in his head. _‘Mhmm, I want to devour you, Lance.’_

“Fuck.” Lance squeezes his eyes shut. There's a certain fear that he can't help, but mostly his belly is warm with growing arousal. Shiro's claw brushes his skin lightly but the sensation soon disappears. The looming body behind him moves back, away.

_‘I've frightened you. I'm sorry, Lance. Maybe this really was a bad idea.’_

Lance turns around, baring his evident hard-on and flushed skin. “I'm not scared of you,” he repeats from earlier, leveling his gaze on the xenomorph. His eyes soften when he sees Shiro hunch even more, trying to seem smaller.

His tail swishes low like a reprimanded animal.

“Come here and give me some more of that spit lube. It’s not poisonous or acidic, is it?”

Lance can practically hear the roll of Shiro’s eyes. _‘Would I offer it if it was?’_

When Lance reaches a hand out for Shiro’s mouth the xenomorph tilts his head out of reach, instead leaning over Lance’s shoulder and opening his mouth. The thick, slippery saliva drips from his jaw and lands on Lance’s lower back, following the line of his spine and down between his ass.

“Oh, okay wow.” Curving his hand back Lance rubs a finger against his hole, spreading the fluid. “That’s actually very efficient. Wait, have you done this before?”

 _‘No,’_ Shiro huffs, leaning back so the bulk of his body isn’t looming over Lance. ‘ _Who would want to use such a thing?’_ He settles in a crouch, hands resting on the floor before him. His tail arches up over his head, the tip flicking idly.

Lance shrugs. “If I had alien lube spit, I’d make good use of it.” Pushing one finger into himself Lance hums. It’s been a while since he’s had anything inside him, but the stretch isn’t painful. “Mm.” He moves over to the bed and kneels, reaching behind himself easier.

_‘Do you do this often?’_

“What, finger myself? Maybe?” Lance swirls and wiggles his finger. When he glances over Shiro’s head is tilted toward him, possibly watching. Lance gets flustered suddenly and huffs. “Do you often _watch_ people fingering themselves?”

_‘I’d watch you do it every time, if I was allowed.’_

“S-Shiro, you can’t just say that!” Lance’s face blooms a bright red. “You don’t think this is weird?” He tests a second finger at his hole before slowly pushing it in alongside the first. Absently he wonders if asking Shiro to bottle his saliva for his own personal use would be weird. Then decides a second later that yes, it would be. “That you’re just watching—you are watching, right?”

 _‘You said I wasn’t allowed to help,’_ Shiro points out, sounding a little put out. _‘I could shift back and—’_

Lance shakes his head, curling his fingers when they’re knuckle deep. “No,” he pants, rubbing and scissoring. “Not if it causes you pain.”

_‘You’re lovely to watch.’_

“Shiro,” Lance groans, cheeks flushed. It might be the weird pheromones in the air but he suddenly blurts out what’s been on his mind for months. “I wanna date you.”

 _‘Is that…’ S_ hiro hesitates. He’s a little hard to read in this form, since his face doesn’t change. _‘Some kind of kink?’_

“What? No!” Biting his bottom lip to stifle a moan Lance rolls his hips to fuck down onto his fingers. The bed beneath him bounces with the motions. “Been thinking about it for months.”

 _‘Dating me?’_ Shiro sounds skeptical and Lance can’t really blame him. _‘Because I’m a—’_

“Super hot guy who’s funny and considerate and selfless? Yeah.” Lance eyes Shiro and his gaze drops down to the xenomorph’s crotch. “When are you going to show me your dick?” He blurts out. “Oh god, is there some kind of truth serum in your spit or what?”

Suddenly Shiro is right there, so close Lance can feel hot breath on his skin. _‘You won’t like it,’_ Shiro murmurs, mouth never moving. _‘It’s alien.’_

“Yeah, we’ve already covered this? Everything alien about you is making my dick rock hard so no worries there.” Lance slides a third finger against his rim. “And besides, how will I know how many fingers I need to stretch with if I can’t see it?”

Shiro is silent for a beat. _‘Keep going.’_

Lance huffs. He watches as the xenomorph that could possibly be his boyfriend walk around him, steps silent. Turning to look back over his shoulder Lance sees Shiro’s head level with his ass. Opening his mouth to ask what Shiro’s doing Lance suddenly feels Shiro’s long, thick tongue push against his fingers.

“Oh, you’re...okay, this is really happening.” Lance’s cock bobs against his belly when Shiro’s tongue wiggles in beside his fingers, spreading more slick.

 _‘I’m helping,’_ Shiro points out, moving his tongue in broad flicks.

Lance can’t help but bend over, his free hand smacking against the bed to hold him up. “Fuck, Shiro!”

Shiro’s tongue works around Lance’s fingers, twisting and occasionally brushing up against his sweet spot. He eases away from it too quickly, almost teasingly. _‘Sorry.’_ Lance is amazed at Shiro’s ability to talk while his mouth is busy fucking him wide.

“Show me your dick,” Lance says, biting his lip to stifle a moan when Shiro’s tongue leaves him.

Silently the xenomorph walks back around and Lance’s fingers still as he watches this new shift of Shiro’s body.

What emerges from the slit in Shiro’s pelvis isn’t as alien as Lance would have thought and in fact, it’s almost startlingly normal. Lance would easily call himself an adventurous guy and to be honest, he’ll admit that he’s seen a fair share of porn. But Shiro’s dick is mostly familiar in shape, if not for the ribbing on the shaft and the nub-like bumps on the underside. It’s so long that it has to be at least the length of Lance’s arm from fingertip to elbow.

It’s the same dark shade as the rest of Shiro’s body, although the spongy, tapered tip transitions to a deep red color. It glistens with a wet sheen, a natural lubricant coating it. Lance’s mouth drops open in surprise when he notices the barbs at the base.

It bobs in front of him, the tip drooling a clear fluid that looks a lot like the viscous saliva.

It’s almost embarrassing that Lance’s mouth waters. He looks up at Shiro, swallowing audibly. “Can I suck it?”

Shiro startles back a step and Lance’s eyes track the drop of pre that drips from the tip and falls to the floor. The length of Shiro’s tail sways behind him. _‘You’d want to—’_

“Yes,” Lance interrupts suddenly. Eagerly. “Yes, I would. I do. I want to put your massively long alien cock in my mouth, like, right now.” When Shiro remains still Lance jams his fingers inside himself hard to stop from crawling toward the other man, er _—_ xenomorph. He moans and wiggles the digits, trying to speed up the process of stretching. “Please, Shiro?” He asks breathlessly, curling his fingers.

With a few silent steps Shiro approaches slowly, a clicking sound echoing in the room when Lance reaches toward him without hesitation and wraps a hand around his dick. He urges Shiro closer and opens his mouth, licking the tapered tip before he wraps his lips around it and sucks.

It tastes foreign, not as bitter as human cum and almost sweet and tangy.

_‘Lance!’_

The human hums and the vibrations travel straight through Shiro’s cock. It pulses in Lance’s mouth, releasing more pre as it’s stimulated. The overflow drips out around Lance’s lips and wets the shaft.

Lance is on cloud nine, sucking sloppily as he fucks himself with his fingers. When he needs more lube he yanks his hand free and reaches up to pump Shiro’s slick length a few times, then shoves four fingers back into himself. He eyes the barbs at the base and they almost look malleable, though he’ll leave them for another time.

When Lance finally deems himself ready Shiro’s steady panting is echoing in his mind. _‘Your mouth,’_ he says, low. _‘You…’_

Pulling off with a wet slurp Lance grins. His pink lips are puffy and his chin is slick with alien fluids. “Cat got your tongue?”

 _‘I want to return the favor,’_ Shiro says, and they both look down at Lance’s very hard and very human erection that curves against his belly. Pulling his fingers free Lance curls them around his cock and strokes once, twice.

“Yeah, I’d like that.” He leans in and kisses the curve of Shiro’s domed head. “Maybe when you don’t have so many teeth, though.”

Shiro rumbles low in his chest and Lance can’t help but reach out, sliding his fingers over the protruding ribs of his exoskeleton. He pats over where Shiro’s heart would be if he were in human form. “Why don’t we get to the main event, huh big guy?”

It takes a few different attempts at positioning and some bickering but finally Lance guides Shiro to sit on the edge of the bed, tail curved up in the air behind him. Lance takes a few seconds to slide his warm hands along Shiro’s thighs, feeling the hardness and corded muscle there.

The xenomorph form shivers at the touch.

Settling his legs on either side of Shiro’s thighs in a reverse cowboy position Lance feels the slick head of the alien’s evident erection rub against him, pushing but at the same time hesitant. He swipes the tip of his tongue along his lower lip, trying to find a comfortable position. “Your thighs are way bonier in this form,” he mumbles, lifting his ass and placing one hand just a little behind Shiro’s knee. He feels Shiro’s cock brush along the back of his thigh and wiggles his hips until the tip pushes against his hole.

‘ _Lance. I...maybe we…’_

Instead of answering Lance slides an arm under Shiro’s jaw, fingers grabbing at the smooth dome of his head for balance before he starts pushing his lower body down. The pressure against his hole peaks and then the tip of Shiro's tapered cock slips into him almost too easily.

The rumble that reverberates through Shiro's exoskeletal chest echoes through his entire body, Lance unable to stop a moan from slipping out as the length inside of him vibrates. “T-that’s…”

The body behind him tenses. _‘Too much?’_

“Cheating,” Lance corrects breathlessly. “Ugh, you’re like a giant vibrator.”

The tension between them snaps and the sound that echoes in Lance’s head sounds very much like a human snort. _‘You’re taking this rather well.’_

Lance huffs, fingers slipping on Shiro’s head. Sweat slides down his spine. “I think I’m taking it _phenomenally_ , considering the circumstances.”

_‘Don't force yourself. I mean it, I wouldn't be able to live with myself if I hurt you.’_

“I'm not gonna…” Shifting a little Lance braces himself as well as he can. Shiro's dick is intimidating but so far there's no pain from the alien intrusion.

Snickering to himself at his own joke Lance rocks back against Shiro's ribbed cock and feels it sink into him inch by inch, and it keeps going like there’s no end to it. When he’s stretched to a point that borders on pain he stops, thighs shaking. That thick, clear liquid drips from Shiro’s jaw and lands on his shoulder.

Lance knew, _knew_ there'd be no way he could take it all, his body isn't _made_ to take anything this big. But _fuck_ , if he wasn’t going to try. He tries pushing himself down a little more.

 _God, Shiro is huge_.

Shaking the thought from his head Lance bites his lower lip, trying to force himself to relax. He rocks his hips from side to side, taking another half an inch. “Shit, Shiro,” he pants, reaching back blindly and wrapping his hand around what won’t fit inside of him. It spans the length of his palm. “Oh, fuck.”

The body behind him becomes still. _‘Are you hurt?’_

“No!” Lance twists his wrist and squeezes. “You’re just.. Really big.” Shiro’s chest rumbles and Lance lets out a breathless laugh. “Are you purring?”

 _‘Your body is so tight,’_ Shiro says instead of answering. His clawed fingers flex in the corners of Lance’s vision, no doubt wanting something to hold onto. _‘Hot, soft, mine.’_

Lance flushes and moves his hands to rest on Shiro’s legs. “I uh, didn’t know you were the possessive type.”

Shiro’s chuckle echoes in Lance’s head, the sound low and warm. _‘Sorry, it’s instinct.’_

Lifting himself up Lance wastes no time lowering himself down, feeling things out for a few thrusts before he falls into an awkward rhythm. His arms strain as he begins bouncing in Shiro’s lap, on Shiro’s dick that he’s becoming so used to as it splits him open. He feels the foreign intrusion deep, rubbing oh so perfectly against his insides.

“This feels amazing.” Sticking his ass out Lance lowers down, hips rocking from side to side. He places a hand on his belly and wonders if he can feel Shiro there. Just the thought makes his cock twitch and Lance slides his hand down to stroke it, smearing his own pre along the shaft. It seems meager compared to what Shiro’s cock drools out.

Leaning his massive head over Lance’s shoulder Shiro opens his mouth slightly and lets his saliva drip down onto Lance’s pink cock, over his balls and onto the thick muscle of his own thighs. Lance moans at the feeling of it dripping over him, his cock bobbing lewdly as he jacks himself while rocking back onto Shiro’s dick.

“Shiro,” he pants, rubbing his cheek against the side of Shiro’s head. The shine of it has fogged up from his hot breath. “I dunno how long my legs can keep this up.”

_‘Want to change positions?’_

Nodding, Lance lifts himself and drops down a few more times before he finally pulls off and flops onto the bed. His hole feels empty, his body thumming with adrenalin and already aching in the best kind of way. He looks at Shiro and Shiro looks at him. “Uh, how about doggy style?”

Shiro’s head sways in a nod and Lance slips off the bed, easing down onto the floor.

The metal is a cold reprieve against his hands and knees and Lance shivers, feeling Shiro’s saliva drip on his ass a few seconds later. It lands on his cheek and he huffs, amazingly aroused by such a thing. Reaching back with one hand Lance spreads himself while his other hand gropes blindly for Shiro’s head and yanks it closer. “Hurry up, Shiro.”

_‘So impatient.’_

A glob of fluid drips onto Lance’s hole and he moans, rocking his ass in the air. His hands return back to the floor and he tilts his chest down so his butt sticks up even higher.

Shiro moves his body up, his inverted legs spread around Lance and the claws on his feet digging into the metal floor. His cock rests hard and heavy against Lance’s back and the human licks his lips, reaching back to wrap a hand around it. He jerks what he can reach a few times, then tugs it down so the head slides slick against the makeshift lube coating his hole.

_‘Tell me if I need to stop.’_

Bending his knees Shiro rocks down to impale Lance once more, the hand still wrapped around him squeezing. “Ohh, oh yeah,” Lance pants. Shiro doesn’t go far on his own, too worried he might push too deep. “I’m not gonna break, Shiro,” Lance snorts, guiding more of Shiro’s long cock into himself. When he hits the limit he squeezes again, the xenomorph above him stilling. “Right there,” Lance whispers, thumb sliding over the ribbed lines of Shiro’s cock. “Okay?”

 _‘I’ve got you, Lance.’_ Shiro’s voice is low and rough, and Lance can tell he’s holding back. Reaching forward Shiro presses his clawed hands against the wall in front of them. _‘I’m going to move now.’_

“Please,” Lance moans, feeling those ridges move against his insides as Shiro withdraws, then fucks back in as deep as he’s allowed. Throwing a hand out Lance reaches back and grabs at Shiro’s leg, his body being rocked with the steady movements of Shiro’s hips. The xenomorph never once pushes past the limit Lance had set.

 _‘You feel so good,’_ Shiro purrs, claws scratching grooves in the wall. He fucks his hips a little faster, feeling Lance’s body tighten. ‘ _Perfect, warm,_ **_mine_ ** _.’_ The last word is almost unintelligible.

“Shiro?” Lance hiccups, jerking back and forth. His knees are going to be bruised tomorrow, there’s no doubt about that. The dark length of Shiro’s dick never once leaves his body, the tip pulsing at his rim before it fucks back into the willing body. At one point Shiro angles his hips a little differently and it pushes him right up against Lance’s prostate.

Lance nearly wails at the sensation of being so full as he’s pounded into, fingers slipping on the floor. “S-Shiro,” he pants, sweat slicking his body. He’s rocked with the constant movements of their fucking and when no response comes Lance’s stomach clenches. “Shiro!”

All movement stops abruptly and Shiro’s voice in his head is rough like a growl. _‘What? What is it?’_ Shiro drags out slowly and the feeling of every upraised rib leaving his rim makes Lance muffle a moan against his arm. The thick weight of Shiro’s cock rests against the cleft of Lance’s ass. _‘Did I hurt you?’_

“No! Fuck,” Lance’s knees give out and he lays on his belly on the cool floor. His ass is gaping, hole clenching around nothing. “Just, just me a second. Are you even close—ah!”

Shiro licks a stripe up Lance’s ass, then repeats the motion only this time his tongue slides wetly between Lance’s cheeks. It catches on his rim and the younger man moans brokenly, cheek pressed to the hard floor. Reaching back with one hand Lance spreads himself, lifting up on his arm to look over his shoulder.

The xenomorph is close and gently rests the side of his face on Lance’s pert ass. Shiro’s head dips in a barely perceptible nod and Lance wonders if he’s scenting. Before his researcher’s brain can think too much about it Shiro’s mouth opens and his tongue slides out, the dripping tip wiggling into Lance and stuffing him full with one thrust.

Lance’s arm gives out from under him and his head drops back against the floor, pain ricocheting across the side of his face as he moans out Shiro’s name. His cock twitches between his belly and the floor, Shiro’s tongue undulating inside of him and pushing the limits of his body.

A sudden flick of the slippery appendage has Lance letting out a strangled shout as his release paints the floor beneath him in streaks of white. Shiro keeps licking at his insides, Lance’s cock jerking as the last few jets of cum shoot from the tip.

Tears slide down Lance’s face and he’s not sure if they’re from the pain in his cheek or the pleasure Shiro is leading him through. A soft whimper slips past his lips when the tongue retracts, leaving a viscous layer of saliva on his rim and ass.

 _‘You’re crying,’_ Shiro whispers, body hunching over Lance’s. He nudges his head against a warm shoulder. _‘Lance?’_

Pushing off the ground Lance rolls away from the mess and onto his back to look up. Shiro has to retreat a step and tilt his head to be able to see Lance properly. “They’re good tears, don’t worry.” Lifting a hand Lance wipes the wetness on his cheeks away. “This is the best sex I’ve ever had,” he confesses and it might be his imagination but Shiro’s chest puffs up a little in pride.

Warm hands touch Shiro’s head and Lance slides his fingers along the dark ridge spanning the length, then presses his fingers where Shiro’s ears would be on a human and guides his head down.

He kisses the smooth dome, then moves down lower where saliva drips from Shiro’s jaw. He hesitates for only a second before he kisses Shiro there, lips wet against the foreign texture. The rumbling sound starts up in Shiro’s chest and Lance moans when he feels the notched tail loop above his knee and wrap around his thigh.

When Shiro leans his head back Lance grins, lifting his arm to wipe across his mouth. “That was weird, right?” He pushes at Shiro’s chest to get him to back up, the tail sliding free from his leg. “Too weird? It was really wet but not unpleasant!.”

 _‘Lance,’_ Shiro growls. It echoes in the room and Lance shivers despite the humid heat. _‘You really are fearless.’_

“No, that’s not it.” Getting to his feet Lance walks toward Shiro. “I’m just not afraid of _you_ , Shiro. No matter what form you’re in.” He touches the xenomorph’s shoulder, then traces a finger along one of the dorsal spines curving from his back. “You might surprise me with a few things in this form, but you’re still you.” Lance smiles a little softer, then pats Shiro’s head. “Sorry, got a little too sappy. Let’s keep going.”

Turning around Lance goes to kneel on the floor but Shiro’s tail stops him. It slithers across his hip and the pointed tip arches away from him, that bend pushing against his stomach until he takes a step back. Lance looks over his shoulder. “What’s wrong?”

Without a word Shiro guides Lance over to the side of the room, in front of the floor-length mirror. When Shiro speaks, the sound is low and soft in Lance’s head. _‘Put your hands on the mirror.’_ Lance does as instructed, the cold glass like a sharp bite against his skin. _‘I’m not going to hurt you,’_ Shiro promises but Lance shakes his head because he’s not worried, not about that. Not even when Shiro’s clawed hands come up and wrap around his middle, grip light but secure. The sharp tips at the ends of his fingers dimple the skin of Lance’s stomach.

That cool, thick saliva drips down Lance’s backside and onto the floor. The slick length of Shiro’s dick slides bumps the back of his thighs and Lance turns to look over his shoulder, finding Shiro’s head inches from his own. His mouth forms a perfect o when Shiro angles his hips to rock forward, feeling thicker and bigger than ever before as he slides home. “S-Shiro,” Lance moans, pushed to his limit with one deep thrust.

Shivers of pleasure course through Lance  and he almost blacks out at the feeling of Shiro all around him, inside of him. The position is strange in that Shiro’s body is slightly crouched, his cock thrusting up slow and deep, rolling Lance up onto the balls of his feet.

 _‘Look at yourself,’_ Shiro murmurs. Lance leans his head back to rest against the space between Shiro’s neck and the loop of his extended collarbone. He can feel the ribs of Shiro’s exoskeleton against his back.

In the mirror Lance sees a mess, his body covered in a sheen of sweat that’s broken out across his flushed skin. His eyes are dark, his mouth slack as his body is rocked in rhythmic motions. Shiro’s hands are dark at his sides, lethal but gentle as they hold him. “I look like a hot mess,” he laughs, fingers slipping on the glass.

 _‘You’re beautiful.’_ Brilliant red sprawls across Lance’s cheeks. _‘Touch yourself.’_

Reaching down with both hands Lance grabs his hardening dick, the cool touch making him whimper. With one hand he squeezes the base and the other jacks the rest, thumb swirling over the slit at the tip. “I’m already close,” he mumbles, breath fogging up the mirror. “Feels so good, Shiro.”

An inhuman screeching sound comes from within Shiro’s chest and it makes the hair at the back of Lance’s neck stand on end. Shiro’s grip tightens and begins pounding into Lance faster, the bend of his body pushing his chest against the human man’s back. His drool drips down Lance’s chest and over a peaked nipple. _‘Me too.’_

“A-are you gonna..” Lance trails off, head lolling against Shiro’s neck as each thrust presses right up against his prostate, battering against it ruthlessly. He’s a babbling mess, coherent thought drifting further and further away. “ _Inside_ me?”

_‘I’m going to mark you as mine.’_

“Yeah, please.” The younger man rocks up onto his toes with the thrusts. He’s so close. “Come on, Shiro,” Lance pants, limbs heavy and flushed. He does his best to tighten his body and squeeze around Shiro.

Every push and pull of the xenomorph’s cock within Lance sends the younger man teetering toward the edge, his body pliant and soft compared to the harsh body behind him, Shiro’s thrusts becoming frantic and bruising. He hisses and clicks in random intervals, Lance mumbling filthy words that push Shiro toward the edge.

“Come on, baby. Fill me up. It’ll feel so good, I promise. I wanna feel good for you.”

And with a low growl Shiro shoves in with a sharp snap of his hips, pushing in as far as Lance can take before he cums within the warm vice of Lance’s body. His fat cock pulses out wave after wave of cum, unloading the thick fluid until there’s no space left in Lance’s ass and it leaks out around the dark shape of him stretching the rim.

 

Lance watches it all in the mirror and the way his belly swells slightly at being filled has his own cock pulsing out ropes of cum that sully the mirror. They drip down the glass, Lance’s head lolling back against Shiro’s shoulder as his eyes watch cum slide down his thighs to drip onto the floor.

After what feels like hours Shiro touches Lance’s hip gently as he shifts, every nub and ridge rubbing on the way out and making Lance moan like a cheap whore. At last the shaft drops free with a wet sound, the tip still dribbling cum. Shiro moves back a step.

Without Shiro there to keep him up Lance’s knees give out and he slumps forward, a warm, human arm wrapping around his middle. “I’ve got you,” Shiro says, his voice no longer a brush in Lance’s mind.

“I gotta take a shower,” Lance mumbles. He feels sleepy and his body won’t cooperate with what he wants it to do. His fingers twitch but Shiro gathers him up into his arms as if he weighs nothing. “I’m gross.”

Burying his nose in Lance’s hair Shiro inhales deeply and hums, carrying him to the bed. “You still smell good to me.”

“Cause I’m covered in your cum.” Lance laughs but it quickly turns into a yawn. He lays his head on Shiro’s shoulder and closes his eyes. “Shower.”

“I’ve got you,” Shiro repeats. He kisses Lance’s forehead. “Rest now.”

Lance mumbles incoherently and drifts off to sleep within a few seconds, warm and comfortable in Shiro’s arms.

 

* * *

 

The next time Lance wakes up he's laying on a soft bed and the scent of freshly washed sheets is all around him. He groans at how  _ warm  _ he feels, blindly reaching down to push at the sheet and kick it away.

As soon as his legs move he freezes, a throbbing ache radiating from the base of his spine all the way to his thighs. “Fuck,” he mumbles, deciding he can bear the heat as long as he doesn't have to move. 

The mattress shifts beside him and Lance's brow furrows. He cracks an eye open to see Shiro with his head pillowed on a hand watching him, his warm grey eyes worried. “Hey.”

“H-hey,” Lance says, suddenly pushing up on his arm. He uses is free hand to brush his hair back, hoping he doesn't look half as bad as he thinks. “What's up?” Shiro raises a brow. Suddenly the memories hit Lance like a truck, the ache in his body making more sense as the haze of sleepiness begins to fade. “Oh!”

“Are you feeling okay?” Reaching out Shiro brushes his fingertips along Lance's bruised cheek. The touch is light, careful. 

“I feel great.” Lance shifts a little so he can face Shiro properly. It's not pain he feels, just a hearty ache that tells him he won't be doing cartwheels any time soon. “How do  _ you  _ feel?” 

A smile breaks out across Shiro's face, slow and warm. “Normal. Thanks to you.” He leans in, thumb sliding gently across Lance's cheek. “Can I kiss you?” He asks boldly. 

Lance grins, tilting his head to kiss Shiro's palm. “You don't really have to ask, Shiro.”

Closing the space between them Shiro kisses Lance, tentative but slowly adding more pressure and a bit of (human) tongue. Lance shivers at the memory of what his other form’s tongue can do, opening his mouth a little wider and licking into Shiro’s.

A hand settles on Lance's hip, the weight warm and heavy. When Shiro pulls back Lance tries to chase his lips, eyes opening in slow blinks. “You're gorgeous,” Shiro whispers. 

Heat blooms on Lance's face and down his neck. “You're not too bad yourself.” 

Adjusting his grip Shiro rolls into his back, bringing Lance with him to rest against on top of him. Shifting his legs a little Lance gets comfortable, folding his arms across Shiro’s broad chest and resting his chin on them. 

Shiro dances his fingers along the small of Lance's back. “Storm’s passed.” 

“Mhm. We can go back up then?”

Shiro's hands rest on the curves of Lance's backside. “Yeah, I started booting the systems up a little before you woke up. We can leave within the hour.”

“How am I gonna explain this limp?” 

“You're creative.” Shiro squeezes the soft skin of Lance’s ass. His voice is nonchalant. “Or you could tell the truth.”

“Yeah? You wouldn’t mind?” Lance’s heartbeat is loud, his smile bright like the afternoon sun. 

Shiro trails his hands back up Lance’s skin, drawing lazy and obscure patterns. He glances away, cheeks tinted a light pink. “I wouldn’t mind everyone knowing you’re my boyfriend.” 

“Oh god,” Lance groans and Shiro’s attention snaps back to him, the other man suddenly alert. “You’re too cute,” Lance bemoans, shaking his head. “How is it possible for you to be this cute? You’re like, eight feet of lethal alien.” 

“Only seven,” Shiro corrects, shifting Lance up a little so he can rub their noses together. He moves slowly to roll Lance back onto the bed and sits up, dragging the sheet up to Lance’s hips. “I’m going to go send a transmission to the main ship, tell them we’ll be there in a few hours. I’ll bring you some painkillers and a water packet.” 

Lance watches Shiro stand up, eyes roaming over the broad expanse of his back and the underwear stretched tight over his ass. He hums appreciatively. “I’ll be here.”

Turning back around after tugging a t-shirt on Shiro kneels on the bed and gives Lance one more kiss. “Good.” He smiles before leaving the room, Lance shifting to lie on his stomach and stretch out across the mattress. He replays the memories from a few hours ago and buries his smile into the pillow, punching the fluffy fabric.

Mission accomplished. 

 

**Author's Note:**

> Thank you for reading!! 🖤🖤
> 
> Find me on [tumblr](http://kuroshiroganee.tumblr.com/) and [twitter!](https://twitter.com/Kuroshiroganee)


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